In 'Signal-based Selling,' we emphasize the importance of using prospect behavior signals and historical intent to customize outreach messages. By analyzing prospect visits to the pricing page and historical intent in the CRM, personalized automated messages at scale can be achieved. The video suggests using prospect behavior, such as revisiting the pricing page after a closed lost deal, as a basis for customized outreach. It highlights the significance of crafting personalized messages based on signals and historical intent, and demonstrates how a RevOps person can use signal-based selling to combine historical intent, website engagement, and new developments for personalized messages.